1. Field of the Invention
The present invention relates to a wiring for an image-pickup apparatus.
2. Description of the Related Art
Recently, the image-pickup apparatus such as digital cameras in which CCD and CMOS are assumed to be an image-pickup element has come to be used widely. A remarkable increase of a pixel count of CCD and CMOS in recent year leads to speed-up of driving frequency and increase of reading data size (See Japanese Patent Laid-Open No. 2009-032765). Therefore, Japanese Patent Laid-Open No. 2009-032765 discloses a LVDS (Low Voltage Differential Signaling) transmission system so as to transfer the data from the image-pickup element to the signal processing part. The LVDS transmission system attempts the speed-up of the transmission speed and the decrease in power consumption by using a differential signal with small amplitude which contradicts (differs in the polarity) mutually.
However, the number of wiring doubles compared with the systems other than the differential signal transmission system when the signal transmission system such as LVDS is adopted. Therefore, the area of the substrate which transmits by using the differential signal transmission system increases while the control signal of the image-pickup element increases, and the miniaturization of the main body of the digital camera is disturbed.
In addition, physical arrangement of grounded wiring and the signal line should be controlled so as to keep not only the differential mode impedance between two signal lines but also the common mode impedance within the predetermined range in the differential signal system. However, a lot of metallic parts which cause the disturbance of the impedance in the camera housing are arranged. Therefore, if the metallic parts come close the differential transmission signal, the impedance value is disturbed and the signal characteristic decreases.